1. Field of Application
This invention relates to packaging machines; and more particularly to machines which form packages from unsupported flexible material, fill such packages with bulk materials to selected weights, and seal such filled packages, all in a continuous and automatic manner.
2. Description of the Prior Art
More and more items are being marketed today in flexible containers, such as clear plastic bags or pouches; printed of course to indicate the contents, supplier and other usual information. This form of packaging is particularly suitable, and has in fact been widely used, for granular type materials like coffee, sugar, cocoa, dry milk, soaps, and many other powders. Rigid type containers (such as boxes, cans, jars, etc.) are generally more expensive to handle and store then flexible containers; and the equipment for moving rigid type containers to and through the filling process is usually more complex then that required for flexible containers. In addition flexible containers provide a more versatile container during use (because its size can be reduced as it is emptied); and one that is more easily disposed of when it is empty. After all, one must remember that a significant number of todays problems are ecological, that rigid containers (like boxes, cans, and jars) are bulky even when empty, and are usually not bio-degradeable, while most flexible containers are of insignificant size when empty, and are made from material which is bio-degradeable.
Much equipment exists for the filling of such flexible containers; but equipment such as that shown in U.S. Pat. No. 1,979,492 granted to John Russell on Nov. 6, 1934 for Method of And Apparatus For Filling Bags With Powdered Or Granular Products, and that shown in U.S. Pat. No. 2,778,387 granted to William R. Diehl on Jan. 22, 1957 for Filling Machine, are only usable with individual containers and thus do not readily lend themselves to continuous automated type operations. Even at that the mechanisms shown are relatively complex in construction and operation. The weighing system of Russell requires the constant re-circulation and re-handling of the material to be packaged which not only adds to the cost of packaging same but also may affect the purity of the material being packaged.
In an attempt to automate the operation of flexible container filling some available equipment, such as that shown in U.S. Pat. No. 3,607,574 granted on Sept. 21, 1971 to Toshihiko Satake for Automatic Packaging Apparatus, utilize tubular stock in continuous roll form. But such equipment quite often still requires movement of the material to be packaged along a path separate and distinct from the tubular stock in order to facilitate the weighing thereof; and relatively complex and costly equipment for transporting the container to be filled to a position to receive the material (or of the material to the container). Subsequent sealing of the container in this type of equipment presents additional problems; while the user of this form of equipment must maintain an inventory of many sizes of tubular stock or greatly limit the packaging operation, by available sizes.
Other available flexible container packaging equipment, such as shown in U.S. Pat. No. 3,538,676 granted on Nov. 10, 1970 to William R. Runo et al for Packaging Machine, utilizes sheet stock and suitable tube forming equipment. Here again the material to be packaged must move along a separate and distinct path to be first weighed before entering into the container forming path. Runo et al dictates the use of highly complex web feeding equipment in order to feed the web stock to and through the tube former and the heat sealer. In addition, equipment such as that shown by Runo et al requires separate, distinct, and quite complex heat sealing units for effecting the vertical seal (to form the tube) and the horizontal seals (to form the bottom and top seals of the container).
Simpler web feeding equipment such as that shown in U.S. Pat. No. 2,913,192 granted on Nov. 17, 1959 to John T. Mullin for Tape Drive Mechanism, has been designed; but such mechanisms are more readily usable in the less demanding environment of tape equipment as shown in the patent. The mechanism is, in itself, quite peculiar in construction rendering it somewhat suitable for the narrow width of recording tapes but quite unsuitable for feeding webs to and through flexible container forming and filling equipment.
Other available equipment for forming flat stock into tubular material and then into flexible containers is shown in U.S. Pat. No. 3,729,359 granted to Claude E. Monsees on Apr. 24, 1973 for Continuous Tube Sealer. Here again the forming of the vertical seal is separate and distinct from the horizontal seal and is accomplished by relatively complex and expensive equipment. The controls, both mechanical and electrical, required in effecting separate and distinct vertical and horizontal seals are usually quite comlex and therefore more costly.
Less complex and costly heat sealing equipment are generally known, as shown in U.S. Pat. No. 2,730,161 granted on Jan. 10, 1956 to Nicholas Langer for Heat Sealing Machine Of The Termal Impulse Type and Method; and as shown in U.S. Pat. No. 3,490,981 granted on Jan. 20, 1970 to Frank G. Shanklin for Apparatus For Heat Sealing Plastic Film. These constructions, however, are not all suitable for use in substantially vertically disposed and continuously operated equipment for filling flexible containers with bulk material. In addition neither disclosure describes the requisite mechanical and electrical controls for use in such flexible container forming and filling equipment.